Digital multimedia watermarking for source identification

ABSTRACT

A system and method for communicating a device&#39;s capabilities uses a digital watermark embedded in content data. The watermark includes parameters concerning a source unit&#39;s communications capabilities. The watermark is embedded within content data, such as multimedia data, of a data packet. A destination unit, upon receiving the data packet detects if a watermark is present, and if so extracts the source&#39;s capability parameters from the watermark. The destination unit then negotiates with the source unit to use certain capabilities based on the source capability information contained in the watermark.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to communicating information using digitalwatermarks.

[0003] 2. Description of the Related Art

[0004] The technique of marking paper with a watermark foridentification is as almost as old as papermaking itself. With theadvent of digital media there are many techniques for applying thisancient art to our new technologies. Such a watermark, applied todigital media, is referred to as a digital watermark. A digitalwatermark is described by M. Miller et al., A Review of WatermarkingPrinciples and Practices, in Digital Signal Processing in MultimediaSystems, 18, 461-85 (K. K. Parhi and T. Nishitani, Marcell Dekker, Inc.,1999), as a piece of information that is hidden directly in mediacontent, in such a way that it is imperceptible to a human observer, buteasily detected by a computer.

[0005] Although the applications of using digital watermarks differ fromthe applications of using paper watermarks, the underlying purpose andapproach remain the same. The conventional purpose of using a digitalwatermark is to identify the original document, identify a legitimatedocument or prohibit unauthorized duplication. The approach used inapplying a digital watermark is much the same as in watermarking ofpaper. Instead of using mesh to produce a faint indentation in the paperproviding a unique identifiable mark, a digital pattern is placed intoan unused area or unnoticeable area of the image, audio file or fileheader. Digital watermarks have also been used to send informationconcerning the message in which the watermark is embedded, includinginformation for suppressing errors in signal transmission andcalibration information. These conventional uses of watermarks, however,fail to fully integrate an intelligent watermark capable of supplyinginformation along with the original signal, image or packet of data.

[0006] More specifically, prior digital watermarking techniques sufferfrom the shortcoming of relying on source identification being tied intothe network transport protocol. Conventional source identification andauthentication schemes use a source identification field embedded in apacket header by the network or transport layer for ascertaining sourceorigin and authentication. Since network and transport layer headers getstripped off of a packet by those layers, these schemes limitidentification and authentication to being performed by the datatransport or network protocols.

[0007] Current fallback schemes to support the capabilities of, and tobe compatible with, preexisting and deployed equipment, referred to hereas legacy equipment, also inhibit the growth and deployment of new andadvanced features in multimedia voice, video and data equipment. Forexample, in the military radio environment LPC-10e vocoders (voiceoperated recorder), which use linear prediction compression (LPC), havebeen in use for years and are widely deployed. However, performance ofthe LPC-10e vocoder is inadequate in severely degraded background noiseenvironments. Newer technologies, such as in the Federal Standard MELP(mixed excitement linear processing) vocoder, have significantly reducedbackground noise effects. The capabilities of such newer technologiesoften go unused because currently deployed fallback mechanisms defaultto the lowest common denominator capabilities of the communicatingdevices. That is, these fallback schemes reduce the operating capabilityof the deployed equipment to the lowest capability level of the devicesin communication (e.g. to the capabilities of the legacy LPC_(—)10evocoder). Accordingly, the advanced capabilities of new equipment goesunderutilized until all legacy equipment in a network is upgraded.

[0008] Even after the legacy equipment leaves the network, the voicedata streams present in the network and that were generated to becompatible with the LPC-10e vocoders remain in the legacy LPC-10ewaveform even though such a waveform is not required for operation oncethe legacy equipment is removed from the communication network. This isdue to the fact that the newer radios are not capable of discriminatingnew equipment sources from legacy equipment sources purely from thetransport layer information in the transmitted data stream. Thisprevents the new equipment from automatically negotiating capabilitieswith other devices to operate with the greatest capabilities common tothe communicating devices.

SUMMARY OF THE INVENTION

[0009] Therefore, in light of the above, and for other reasons that willbecome apparent when the invention is fully described, an aspect of theinvention is to automatically negotiate communication parameters betweencommunicating devices based on the capabilities of those devices. Thiscan be accomplished by including capability information in a digitalwatermark embedded in an information field of a message transportedbetween the communicating devices.

[0010] A further aspect of the invention enables a device in acommunication network to negotiate a common set of communicationcapabilities for devices in the network to use, without relying oninformation contained in a packet header.

[0011] Yet another aspect of the invention generates a digital watermarkincluding information concerning a device's capabilities.

[0012] A still further aspect of the invention detects a digitalwatermark in an information field of a data received from a source unit,extract from a watermark in the packet information concerning the sourceunits capabilities.

[0013] The aforesaid objects are achieved individually and incombination, and it is not intended that the invention be construed asrequiring two or more of the objects to be combined unless expresslyrequired by the claims attached hereto.

[0014] The above and still further objects, features and advantages ofthe invention will become apparent upon consideration of the followingdescriptions and descriptive figures of specific embodiments thereof.While these descriptions go into specific details of the invention, itshould be understood that variations may and do exist and would beapparent to those skilled in the art based on the descriptions herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a block diagram of a communication system using adigital watermark to convey information concerning a source processor'scapabilities.

[0016]FIG. 2 is a flowchart illustrating a process for negotiating a setof communication capabilities.

[0017]FIG. 3 is a flowchart illustrating a process for extracting adigital watermark containing information concerning a source'scapabilities.

[0018]FIG. 4 is a block diagram of a wireless radio source unit thatgenerates a watermarked speech frame that includes informationconcerning the capabilities of the radio.

[0019]FIG. 5 is a block diagram of a wireless radio destination unitthat receives and processes a watermarked speech frame that includesinformation concerning the capabilities of the wireless radio sourceunit shown in FIG. 4.

[0020]FIG. 6A is a diagram illustrating an operational process of thewireless radio source unit shown in FIG. 4.

[0021]FIG. 6B is a diagram illustrating an operational process of thewireless radio destination unit shown in FIG. 5.

DETAILED DESCRIPTION

[0022] The invention is described below with reference to the abovedrawings, in which like reference numerals designate like components.

[0023] Overview

[0024] The invention uses a signature structure, such as a watermark,that provides control information content embedded in applicationinformation, rather than a passive watermark that provides onlyidentification information. This technique also recognizes the need tobe able to tailor the information content to customize an application ateither a source or a destination.

[0025] A signature, containing information concerning attributes of asource unit is periodically embedded at pseudo-random points in atransmitted data stream allowing the source to watermark a signal, suchas a multimedia signal. Using such a signature to watermark the datastream allows a device at the data stream's destination to identify andauthenticate the source's capabilities. The watermark can contain, forexample, source capability content, including a source ID, operationalmodes and capabilities of the source and application specificperformance parameters.

[0026] The watermark can be inserted after application layer multimediaprocessing has been performed, but prior to the network and transportlayer processing. Accordingly, the watermark is embedded within themultimedia signal prior to network and transport layer headers beingapplied to packets of the data stream. This allows the watermark to beapplied to the data stream without effecting either application-level ortransport-level processing of the digital multimedia data stream.

[0027] A signature is a group of bits that indicate a specific attributeof the source unit, such as a capability that the source unit possessesor lacks. The type of information that can be used as a signatureincludes any source-specific attribute. For example, in a wirelesscommunications system, one or more signatures can indicate the audio andvideo compression capabilities, the application software or operatingsystem revision numbers, the ID number of the source, the audio handsetcapabilities including the number of bits and audio fidelity of thesource. The signature can be applied as a short duration digital signal,and can be placed as a watermark in non-critical points in the datastream, such that its effects on the resulting reconstructed multimediastream are imperceptible to the human. For instance, a signature thatindicates a source unit's capabilities can be placed in the watermark.

[0028] In an audio application, the signature appears as a shortduration pattern placed at non-critical bits in the compressed audiosignal. The non-critical bits can be predetermined so that the sourceand destination units both know a priori which bits in the signal arethe non-critical bits with which the watermark is embedded in thesignal. For example, for the MELP vocoder, the non-critical bits caninclude the least significant bits of the Multi-stage VectorQuantization of LPC coefficients, the Jitter Index bit, the leastsignificant bits of the Second Gain Index, and the least significantbits of the Fourier Magnitudes. For LPC-10e, the non-critical bits caninclude the least significant bits of the reflection coefficients.

[0029] In a video application the signature appears in randomly placedpixel locations in either a still image or a full-motion video stream.For example, in a video code conforming to the H.263 standard, thewatermark can be placed in the least significant bits of theunrestricted motion vectors and the Discrete Cosine Transform (DCT)coefficients. In still image encoding, such as in a JPEG image, thenon-critical bits can include the least significant bits of thequantized DCT coefficients.

[0030] The destination equipment detects the watermarked signature andascertains the source's capabilities based on the information containedin the watermark. This allows the destination equipment to negotiate tohigher levels of capabilities with new equipment that may be present inthe network.

[0031] Since the watermark is not perceptible to a human, it does notsignificantly effect the performance of the multimedia signal to the enduser, in legacy equipment. For example, a 20-bit signature, applied as acontent capabilities watermark to non-critical bits in a compressedLPC-10e bitstream, appears to legacy LPC-10e equipment as a validLPC-10e data message. The legacy equipment passes the bitstream to theappropriate decoding/uncompression unit and reconstructs the audiosignal. Since the signature is applied only at periodic intervals, theend user of the legacy equipment will not perceive any degradation inthe reconstructed voice signal. Upgraded, or new equipment, that uses awatermark detection process, can determine, based on the watermark, ifthe data stream is transmitted from new or legacy equipment, and can actaccordingly to negotiate the highest level of capabilities possible.

[0032] If the destination equipment determines that the data stream issent from upgraded equipment that supports a higher level ofcapabilities than the legacy equipment, it can begin negotiationprocessing to use the upgraded equipment's enhanced multimediacapabilities, rather than remaining in a degraded operational mode inwhich both the source and destination remain in the previouslynegotiated lower capability mode.

[0033] Since the detection and negotiation processes take place betweenthe application and transport layers, it is transparent to the lowerlevels of data processing and is unaffected by further informationtransformation, including encryption, data packing, and data routingtechniques. This means that the watermarked multimedia signal can betreated by routers, relay equipment, etc., as any other random datastream.

[0034] Although the content capabilities watermark is described here asembedded in voice data for use with communicating vocoders, theinvention is not limited to use with voice signals. Rather, it appliesto other types of data as well in which a signature can be embeddedwithout unduly degrading the data, at least as that data is perceived bya user. For instance, the content capabilities watermark can also beembedded in image data, and used by devices that negotiate capabilitiesto communicate the image data. Examples of such devices that lendthemselves to content watermarking include cellular telephones, pagersand other wireless devices, to indicate the status and interworkingcapabilities of these devices, personal digital assistants (PDA's),personal handheld audio devices such as Motion Picture Experts Group(MPEG) audio players, digital video disks (DVD's), compact disks (CD's),and other mass data storage devices.

[0035] Multimedia Authentication Watermarking Architecture

[0036] A block diagram of a multimedia authentication watermarkingarchitecture is shown in FIG. 1, and includes a source processor 1 and adestination processor 6. The source processor 1 includes a multimediaapplication processor 2, a digital watermark signature generator 3, acombiner 4 and a transport/network processor 5.

[0037] The digital watermark signature generator 3 outputs a uniquesignature to the combiner 4. The multimedia application processor 2receives a multimedia data stream such as a voice, video, or datastream, from an application program. The multimedia applicationprocessor 2 compresses, or otherwise transforms the multimedia datastream, and outputs a processed multimedia data stream to combiner 4.

[0038] The combiner 4 embeds the digital watermark signal into themultimedia data stream. For example, the watermark signal can belogically OR'd with the masked data stream at appropriate fields of thedata stream, such as at certain bit positions, depending upon theapplication. These locations are chosen so that they have a minimalimpact on the subjective quality at the destination of the multimediadata stream. The watermark can be applied on a periodic basis tofacilitate the detection process and increase the probability ofdetection of the watermark. The combiner 4 then outputs a signedwatermarked multimedia data stream to transport/network processor 5. Thenetwork/transport processor 5 applies the necessary message headers andcontrol bits, and packetizes the data stream. Accordingly,transport/network processor 5 outputs a data packet, or datatransmission unit, with network/transport headers applied to a datafield that includes the digital watermark signature.

[0039] The destination processor 6 receives the data transmission unitsent by source processor 1. The destination processor includes atransport/network processor 7, a watermark detector 8, a watermarkextraction mask unit 9, a multimedia application processor 10 and acapabilities negotiation processor 11. The transport/network processor 7receives the data transmission unit, or packet, determines if it isdestined for the destination processor 6, and if so removes thetransport and network headers and outputs a processed data unit to thewatermark detector 8. The watermark extraction mask unit 9 generates apredetermined watermark extraction mask corresponding to the watermarksignature generated by the generator 3 in the source processor 1, andoutputs that mask to watermark detector 8. Watermark detector 8 uses themask to extract the watermarked source capabilities signature from thedata unit. The detector 8 determines if a watermark is present in thedata unit and if so, identifies the source by comparing a digitalsignature for the source with the multimedia bitstream watermark. Ifthey match, that information along with the extracted watermark can besent to the capabilities negotiation processor 11, which can track theoccurrences of the watermark and negotiate capabilities. The watermarkdetector 8 outputs the data unit with the watermark removed tomultimedia application processor 10 which performs any decompression orother transformation necessary to recover the multimedia data stream.Processor 10 then outputs the reproduced multimedia data stream, such asa voice, video, or data signal.

[0040] The capabilities negotiation processor 11 keeps track of thewatermark occurrence history by maintaining a time/history record ofthose occurrences. The capabilities negotiation processor 11 takesappropriate action to automatically negotiate the destination processingbased on capabilities information contained in the watermark. Thecapabilities negotiation processor can then determine the sourcescapabilities, and output a control/status signal indicating thoseabilities to a capabilities control unit to initiate the negotiation.The capabilities processor then uses the control/status informationreceived from the source to configure its capabilities to match those ofthe sources to the highest common denominator. For instance, if thecontrol/status signal indicates that the source has the ability toaccept MELP or LPC-10e compressed speech, the capabilities processorconfigures itself to transmit MELP speech, since that speech protocol isthe highest common speech processing protocol that both the source anddestination can understand. Other types of capabilities can benegotiated using the techniques described here. For example, source anddestination processors can configure themselves to select a highestcapability common vocoder, common video compression techniques, etc.

[0041] Also, the source processor can embed in a watermark a group ofcapabilities, such as vocoder type (e.g., MELP, LPC-0e, etc.) and thetype of handset the source is currently using (e.g., an H-250 handset,etc.). When a group of capabilities are embedded in a watermark, thosecapabilities can be negotiated individually or as a group. For example,if the destination processor knows that a certain handset needsadditional low frequency gain to increase intelligibility, it canconfigure its audio equalizer to provide the necessary gain.

[0042] The capabilities negotiation processor 11 can determine when tonegotiate to an improved capability, or fall back to legacy operationalmode based on the time occurrences of the watermark. For instance, ifthe capabilities negotiator has not detected any legacy equipmenttransmissions for a pre-determined length of time, it can switch from alegacy operational mode to an improved operational mode. If thecapabilities negotiator detects a legacy message, the destinationprocessor can fall back into a legacy operational mode for compatibilitywith older, non-upgraded equipment.

[0043] Multimedia Authentication Watermarking Process

[0044] A process for using the multimedia authentication watermarkingsystem shown in FIG. 1, is illustrated in FIG. 2. The multimediaapplication processor 2 of source processor 1 receives a multimedia datastream, such as a voice, video or data stream from a data source (12),and processes that stream to compress or otherwise transform the datawithin the stream (13). The digital watermark signature generator 3generates a predetermined watermark signature that includes informationconcerning the capabilities of the data source (14). The combiner 4combines the generated watermark signature with the processed datastream output from the multimedia application processor 2, and outputs asigned data stream to a transport/network processor 5 (15). One way ofcombining the watermark signature with the processed data stream is tologically OR the watermark signature with the data stream at theappropriate bit positions, depending upon the application. Those bitpositions are chosen so that they have a minimal impact on thesubjective quality of the multimedia data stream at the destination. Thewatermark can be applied on a periodic basis to facilitate the detectionprocess and increase the probability of detection of the watermark. Thetransport/network processor 5 adds the appropriate network and transportlayer headers to the signed data stream and outputs it as a datatransmission unit, such as a data packet (16). For example, in a TCP/IPnetwork environment, the appropriate TCP/IP headers are added to thesigned data packet to route the packet to the destination. Other typesof networks, such as asynchronous transfer mode (ATM) networks, addheaders to route information as appropriate. For instance, in aspace-based network, a packet might be routed using a Proximity-1 linklayer protocol. In that case, the Proximity-1 headers are needed toroute the packets to the final destination.

[0045] The transport/network processor 7 of the destination processor 6receives the data transmission unit, or data packet sent from sourceprocessor 1, and removes communication headers and control informationfrom the packet (16). The watermark detector 8 detects whether thereceived data packet includes a watermark, and if so, extracts it (17).The watermark is analyzed to determine from it the capabilities of thesource (18). Based on those determined capabilities, the destinationnegotiates with the source communication capabilities to utilized insubsequent communications (19). The subsequent communication iscommenced using the negotiated parameters negotiated between thedestination and source (20).

[0046] A more detailed illustration of the process for extracting adigital watermark containing information concerning a source'scapabilities is shown in FIG. 3. Here, the data transmission unit isreceived at the destination processor which detects if it is addressedfor the destination (21). Watermark generator 9 generates apredetermined watermark extraction mask (22). The received datatransmission unit is analyzed to determine if a watermark is present. Ifso, the watermark is extracted (23). The watermark is examined todetermine if it contains capability information about the source unitthat transmitted the transmission unit (24). If the watermark containssource capability information the source unit's capability parametersare detected from the extracted watermark signature (25). Thedestination processor then negotiates communication capabilities withthe source processor (26) and continues with subsequent communications(27). After extracting the capability parameters from the watermarksignature the watermark is removed from the processed multimedia data inthe transmission data unit (28). The processed data is again processedto decompress or otherwise inverse transform the data to recover themultimedia data stream (29) and output that recovered data stream to adestination application.

[0047] If the extracted watermark does not compare with thepredetermined watermark generated by the destination watermarkgenerator, then default, or fallback capabilities are used forcommunication with the source processor (30).

[0048] The watermark generated by the source can be either static ordynamic depending on whether the source capabilities change with time.For instance, prior to a software update, a particular source may onlybe capable of running LPC-10e. After the software is updated, it mighthave the capability to run other vocoders, such as a MELP vocoder. Also,the capabilities may be location dependent. If the source contains a GPSreceiver, or other position determination device, it can change it'scapabilities depending upon it's location.

[0049] It will be understood that the digital watermarking signaturegenerator and the watermark detector can be embodied in software,hardware, or a combination of both technologies. The capabilitiesnegotiation processor can keep track of the watermark occurrence historyand take appropriate action to automatically negotiate the destinationprocessing. The multimedia application processing converts themultimedia bitstream back to the audio/voice/video domain.

[0050] Wireless Radio System Application

[0051] An example of an application that uses digital watermarks fornegotiating between the source and destination units shown in FIG. 1 isa wireless radio system used in a military environment. Wireless radiosin such a system can use earlier, or legacy, vocoders such as an LPC-10evocoder, or a newer, more capable vocoder such as a MELP vocoder. Ablock diagram of a wireless radio source unit 30 is shown in FIG. 4. Thesource radio includes a speech generation unit 31 that converts rawspeech into a sampled signal that is sampled, for example, at a samplinginterval of 22.5 milliseconds. The sampled raw speech is input to aspeech compression unit 32 that compresses the speech according toeither the MELP or the LPC-10e standards. The compressed speech isoutput and supplied to a first buffer 33 that distinguishes the criticalbits 33 b in the compressed speech from the non-critical bits 33 a. Thecompressed speech frame is supplied to a logical AND circuit 34. Alsosupplied to the logical AND circuit is a signature mask output from asignature mask unit 35. The signature mask includes a set of logicalzeros (0's) 35 a and a set of logical ones (1's) 35 b arranged with apriori knowledge of the watermark arrangement. The logical zeros 35 acorrespond to the positions of the non-critical bits in the compressedspeech frame. Logically AND'ing the compressed speech frame bits withthe signature mask results in a compressed speech frame with thenon-critical bits set to zero and the critical bits retaining theirvalue from the compressed speech frame.

[0052] The compressed speech frame output from logical AND circuit 34 isinput to a second buffer 36. The compressed speech frame stored inbuffer 36 includes a first storage area 36 a that includes thecompressed speech frame non-critical bits that have been set to zero 36a and the compressed speech frame critical bits 36 b that make up thespeech frame output from logical AND circuit 34. The speech frame storedin buffer 36 that includes the zero-value non-critical bits is appliedto a logical OR circuit 37. Also applied to the logical OR circuit 37are a set of source capability bits stored in a first area 38 a of asource capabilities buffer 38. Stored in a second area 38 b of buffer 38is a set of logical ones that correspond to the positions of thecompressed speech frame critical bits in the speech frame. The sourcecapability bits stored in area 38 a are set according to sourcecapability information concerning capabilities of the source radio. Thecapability information can include, for example, source vocoder types,source vocoder revision numbers, source ID, etc. The logical OR circuit37 combines the source capabilities information from buffer 38 with thespeech frame recorded in buffer 36. The effect of that operation is tocombine the source capability information with the compressed speechframe non-critical bits. The resulting output of the logical OR circuitis output to a watermarked speech frame buffer 39 that contains awatermarked speech frame having a set of source capability bits 39 a anda set of compressed speech frame critical bits 39 b. Because the sourcecapability bits are located in the non-critical bit positions of thecompressed speech frame, applying the watermark has little noticeableeffect on the speech frame. The watermark speech frame 39 is then outputfrom the source unit 30 and transmitted to a destination radio.

[0053] A destination radio 40 is shown in FIG. 5. The destination radioreceives the watermark speech frame and stores it in a speech framestorage buffer 41. The received speech frame corresponds to thewatermarked speech frame transmitted from source radio 30, and includesa set of source capability bits stored in a source capabilities area 41a and a set of compressed speech frame critical bits stored in acritical bit area 41 b. The destination radio uses the watermark speechframe to extract the source capability information and to extract thespeech information from the critical bit area for reproducing thespeech. A first logical AND circuit 42 extracts the compressed speechframe critical bits from the watermarked speech frame. A data extractionmask, held in a data extraction mask buffer 43, includes a set oflogical zeroes 43 a at locations corresponding to locations of thesource capabilities information within the watermarked speech frame, anda set of logical ones 43 b at locations corresponding to locations ofthe compressed speech frame critical bits within the watermarked speechframe. The data extraction mask applies those logical zeroes and ones tothe logical AND circuit 42 which operates to output the compressedspeech frame with the non-critical bits set to zero. Applying thelogical ones 43 b to the watermark speech frame causes the compressedspeech frame critical bits to be output from the logical AND circuit 42unaltered.

[0054] The watermark speech frame 41 is also applied to a second logicalAND circuit 44. Also applied to logical AND circuit 44 is a signatureextraction mask held in signature extraction buffer 45, which alsoincludes an area 45 a for storing logical ones and an area 45 b forstoring logical zeros. As with the data extraction mask described above,the logical AND circuit 44 applies the signature extraction mask 45 tothe watermarked speech frame, although it outputs the source capabilitybits 41 a unaltered and sets the critical bits 41 b to zero. That is,the logical AND circuit 44 applies the logical ones in area 45 a to thesource capability bits 41 a in the watermarked speech frame and allowsthose source capability bits to pass unaltered. However, the logical ANDcircuit 44 applies the logical zeroes in area 45 b to the compressedspeech frame critical bits 41 b of the watermark speech frame, therebysetting those critical bits to zero. Hence, logical AND circuit 44outputs source capability bits 41 a with the compressed speech framecritical bits 41 b set to zero.

[0055] The source capability information output from logical AND circuit44 is stored in a source capabilities signature unit 46 which includes asource capability signature area 46 a. Unit 46 can also include an areafor storing the critical bits that were set to zero by logical ANDcircuit 44, although those bits need not be retained. The sourcecapabilities unit 46 decodes the source capabilities signature, and fromthat signature determines the source radio's capabilities and outputsinformation to that effect. The source capabilities information caninclude, for example, the vocoder-type, vocoder revision number, ID,etc. of the source radio. This capability information is supplied to anegotiations processor 47 that negotiates communications, or otherparameters with the source radio. The negotiations processor 47 uses thesource capabilities information to determine the common capabilitiesbetween the source and the destination radios based on the sourcecapability signature and the capabilities information supplied by thedestination radio. The source capabilities unit 46 determines thehighest level of source capability commonality between the source anddestination radios and uses that information to negotiate with thesource radio.

[0056] A compressed speech buffer 48 stores the compressed speech framenon-critical bits set to zero 48 a and the compressed speech framecritical bits 48 b. The speech frame in buffer 48 is passed to a speechdecompression unit 49. The speech decompression unit receives from thesource capabilities unit 46 capability information designatingdecompression parameters, such as the type of decompression to perform(e.g., MELP or LPC-10e). The speech decompression unit 49 uses thatinformation for setting parameters for the speech decompression. Thespeech decompression unit 49 operates to decompress the speech framebased on the decompression parameters supplied from source capabilitiesunit 46, and outputs the raw speech signal 50, again at the samplingrate of 22.5 milliseconds.

[0057] In this manner the destination radio 40 can operate with thehighest level of capabilities that are in common with the source radioin order to communicate with the source radio and to process the speechsignal.

[0058] A process for operating the wireless radios shown in FIGS. 4 and5 is illustrated in the flowcharts shown in FIGS. 6A and 6B. FIG. 6Aillustrates the operations performed by the source wireless radio 30 inFIG. 4. Here, an uncompressed multimedia data stream is compressed 51using a compression algorithm available to the source radio.Capabilities of the source unit 52 are determined and that capabilityinformation is used to generate a source capabilities signature 53. Thecompressed multimedia data stream signal is applied to a signature maskthat masks the data stream non-critical bits for use in carrying thesource capabilities information 54. The generated source capabilitiessignature is then applied as a watermark to the masked and compressedmultimedia data stream 55. The watermarked multimedia data stream isthen transmitted to a destination wireless radio 56. The transmission isshown by way of connector A in FIG. 6A connecting to a similar point inFIG. 6B.

[0059] The destination wireless radio receives the watermarkedmultimedia data stream 57, masks the datastream non-critical bits 58,and extracts a signature from the watermark 59. The extracted signatureis used to recover the source capabilities signature from the datastream 60. The source capabilities are determined from the recoveredsource capabilities signature 61. Those source capabilities are compared62 with capabilities of the destination radio 63. Based on the comparedsource and destination capabilities, the highest level of capabilitiescommon to both the source and destination are determined 64 andcapabilities information consistent with that determination is outputfor use in decompression and subsequent communication with the sourceradio.

[0060] Once the signature is extracted from the watermark in operation59, the data stream is then recovered 65. The multimedia data stream isthen decompressed using the determined common source and destinationcapabilities 66. Upon the decompression, the multimedia data stream isrecovered 67 and available for speech reproduction.

[0061] Although watermarks are described above in terms of communicatinga plurality of attributes, alternatively, if desired, a single attributeonly can be embedded in the multimedia data as a watermark for use inconfiguring a destination radio. For example, the single attributeembedded as a watermark can be an indication that the source radiocompressed the speech signal according to the MELP standard.

[0062] Applications

[0063] The systems and methods described here can be applied to manyapplications, including, but not limited to the following applications.

[0064] Military mobile, wireless communication equipment, includingradios, secure terminals.

[0065] Multimedia over IP equipment including voice, video and datacommunications equipment.

[0066] Mobile networking multimedia equipment, including cell-phones,networked radios, network data and video terminals, PDA's, DigitalPaging, Advanced HDTV.

[0067] Point-to-Point, broadcast, multicast, and conferencing multimediaequipment.

[0068] Non-wireless communication equipment, including internet,intranet and point-to-point where known ID, location or usercapabilities is important.

[0069] The methods, systems and apparatuses described here can be usedwhenever two devices must communicate and offer varying service,accommodate different versions or provide flexible interfacing. Forexample, in a mobile client/server environment these techniques can beused to synchronize varying versions of the clients with the server'sresources. For instance, a PDA client might use the digital watermarkingtechniques described here to authenticate its ability to use aparticular feature, allow for conversion of data or provide upgradedservices. Newer PDAs with more capable software can gain access tobetter services/features than can older PDAs that do not have the morecapable software. The digital watermarking techniques described herealso can be used with other devices, such as cellular telephones toidentify the telephone's ability to receive pages or e-mails. An exampleof such a use with telephones is where two telephones use the sametelephone number. During a negotiation process the telephones inform abase station of the services the telephones are capable of providing.One telephone might allow a particular service because that telephone isa newer model that supports newer features, However, another telephonemight be an older telephone that is incapable of the supporting newerfeatures. Accordingly, each telephone informs the base station of itscapabilities by using a digital watermark with information concerningthe telephone's capabilities included in the watermark. The base stationnegotiates with each telephone individually, based on that telephone'scapabilities indicated in the watermark, thereby allowing each telephoneto use the features it has available and to operate with the highestlevel of capabilities that the telephone can support.

[0070] Having described systems and methods for using a digitalwatermark to negotiate compatible capabilities, it is believed thatother modifications, variations and changes will be suggested to thoseskilled in the art in view of the teachings set forth herein. It istherefore to be understood that all such variations, modifications andchanges are believed to fall within the scope of the present inventionas defined by the appended claims. Although specific terms are employedherein, they are used in their ordinary and accustomed manner only,unless expressly defined differently herein, and not for purposes oflimitation.

What is claimed is:
 1. A method of communicating information concerningan attribute of a data source unit, comprising: generating a watermarkbased on said attribute of the data source unit; combining the watermarkwith a data stream from the data source unit, thereby generating a datatransmission unit; and transmitting the data transmission unit to adestination unit.
 2. The method of claim 1, wherein the attribute of thedata source unit corresponds to a capability of the data source unit. 3.The method of claim 2, wherein the attribute of the data source unitcomprises one of a type of voice operated recorder (vocoder), a sourceunit revision indicator, and a source unit identifier.
 4. The method ofclaim 1, wherein the watermark is generated based on a plurality ofattributes of the data source unit.
 5. The method of claim 4, whereinthe attributes of the data source unit correspond to capabilities of thedata source unit.
 6. The method of claim 5, wherein the attributes ofthe data source unit comprise at least one of a type of voice operatedrecorder (vocoder), source unit revision indicator, and a source unitidentifier.
 7. The method of claim 1, further comprising compressing thedata stream according to a source compression algorithm, wherein theattribute upon which the watermark is generated identifies the sourcecompression algorithm.
 8. The method of claim 1, further comprising:compressing the data stream to generate a compressed data stream;detecting a capability of the source unit; generating a signature basedon the detected capability of the source unit; and applying thesignature as the watermark to the compressed data stream to generate thedata transmission unit.
 9. The method of claim 8, wherein the detectedcapability of the data source unit comprises at least one of a type ofvoice operated recorder (vocoder), source unit revision indicator, and asource unit identifier.
 10. The method of claim 8, wherein the datastream includes multimedia data encoded in a plurality of fieldsincluding non-critical fields and critical fields, and wherein saidapplying the signature comprises masking the non-critical fields of thedata stream; applying the signature to the masked fields of the datastream; and outputting a signed data stream having the non-criticalfields of the data stream containing the signature and the criticalfields of the data stream containing the multimedia data.
 11. The methodof claim 1, wherein the data stream includes header information andmultimedia content information, and wherein the watermark is containedin the multimedia content information.
 12. The method of claim 1,wherein the watermark is a digital watermark.
 13. A method ofdetermining capabilities of a data source unit, comprising: receiving adata transmission unit containing a data stream having a watermark, thewatermark containing information concerning an attribute of a datasource unit; and determining, based on the watermark, said attribute ofthe data source unit.
 14. The method of claim 13, wherein the attributeof the data source unit corresponds to a capability of the data sourceunit.
 15. The method of claim 13, wherein the data stream includesheader information and multimedia content information, and wherein thewatermark is contained in the multimedia content information.
 16. Themethod of claim 13, wherein the watermark corresponds to a plurality ofattributes of the data source unit.
 17. The method of claim 13, whereinthe watermark is a digital watermark.
 18. The method of claim 13,wherein the transmission data unit is received at a destination unit,and the method further comprises extracting a signature from thewatermark, determining a source unit attribute from the extractedsignature, determining a destination unit attribute corresponding to thedata source unit attribute, and comparing the source unit attribute withthe destination unit attribute.
 19. The method of claim 18, furthercomprising determining a capability common to both the source anddestination units based on the compared attributes.
 20. The method ofclaim 19, further comprising negotiating a parameter for use incommunicating between the data source unit and the destination unitbased on the determined common capability.
 21. The method of claim 19,further comprising recovering from the received transmission data unit amultimedia data stream, based on the negotiated parameter.
 22. A datasource apparatus, comprising: a data stream processor configured tooutput a data stream; a signature generator configured to generate asignature containing information concerning at least one attribute ofthe data source apparatus; and a combiner configured to receive datastream and signature, to embed the signature as a watermark within thedate stream, and to output a watermarked data unit.
 23. The data sourceapparatus of claim 22, wherein said at least one attribute of the datasource unit corresponds to at least one capability of the data sourceunit.
 24. The data source apparatus of claim 23, wherein said at leastone attribute of the data source unit comprises at least one of a typeof voice operated recorder (vocoder), source unit revision indicator,and a source unit identifier.
 25. The method of claim 23, furthercomprising compressing the data stream according to a source compressionalgorithm, wherein said at least one attribute identifies the sourcecompression algorithm.
 26. The data source apparatus of claim 22,further comprising a transport unit configured to add communicationprotocol information to the watermarked data unit and to output a datatransmission unit.
 27. The data source apparatus of claim 22, whereinthe combiner unit comprises a circuit for logically combining thesignature with the data stream.
 28. A data source apparatus suitable forcommunication with a destination unit, comprising: means for generatinga data stream; means for generating a watermark based on a plurality ofcapabilities of the data source apparatus; means for combining thewatermark with the data stream, thereby generating a data transmissionunit; and means for transmitting the data transmission unit to adestination unit.
 29. A destination apparatus, comprising: a receptionunit configured to receive a data transmission unit having multimediadata containing an embedded watermark, wherein the watermark containsinformation concerning at least one capability of a source data unitoutputting the multimedia data; a watermark detector configured todetect the watermark embedded in the multimedia data; and a capabilitiesunit configured to extract source data unit capability information fromthe watermark and to control operation of the destination apparatusaccording to the extracted capability information.
 30. The destinationapparatus of claim 29, further comprising a capabilities negotiationprocessor configured to negotiate with the source data unitcommunications parameters based on the capability information extractedfrom the watermark.
 31. The destination apparatus of claim 29, whereinthe watermark contains information concerning a plurality ofcapabilities of the data source unit.
 32. The destination apparatus ofclaim 29, wherein the multimedia data contained in the data transmissionunit is compressed according to a compression algorithm employed in thedata source unit, and wherein the source data unit capabilityinformation extracted from the watermark includes informationidentifying said compression algorithm, the apparatus further comprisinga multimedia data decompression unit configured based on saidinformation identifying said compression algorithm to decompress themultimedia data.
 33. The destination apparatus of claim 29, wherein thewatermark detector comprises an extraction mask unit configured tologically combine the multimedia data containing the watermark with adata extraction mask and a signature extraction mask, and to output amultimedia data frame having the watermark extracted and a signaturesignal containing the source data unit capability information.
 34. Andestination apparatus for communicating with a data source unit,comprising: means for receiving a data transmission unit containing adata stream having a watermark, the watermark containing informationconcerning a plurality of capabilities of a data source unit; and meansfor determining, based on the watermark, said plurality of capabilitiesof the data source unit.